Conventionally, there is known a connector which connects a daughterboard and a motherboard (e.g., see JP-A-7-6823). This connector includes a connector plug, which is attached to the daughterboard, and a connector receptacle in which this connector plug is fitted. This connector plug has a housing and plural transmission path blocks housed in this housing. These transmission path blocks are provided to be disposed at a predetermined interval.
These transmission path blocks are planar. Transmission path patterns are formed on one surface thereof, and ground patterns are formed on the other surfaces thereof. These transmission path patterns are micro strip lines formed of single transmission paths. A filter element is provided in each line.
The connector receptacle includes a housing and plural socket contacts housed inside this housing. These socket contacts are provided to be disposed at a predetermined interval. Each of the socket contacts is connected to each of the transmission path blocks.
According to such a connector, impedance matching and reduction in crosstalk can be realized, and noise can be reduced.
However, in recent years, there has been a demand for transmission of signals at low cost. Therefore, a differential signal system, which has a low voltage and a high noise resistance, has started to be used. A connector for differential signals having a micro strip line formed of a pair of transmission paths is used for this differential signal system.
However, even in the above-mentioned connector for differential signals, in the case in which a signal with a high frequency is transmitted, a phenomenon, in which a voltage level of a signal attenuates, may occur on the transmission paths due to an action of a conductor skin effect.
In particular, in the case in which a digital signal is transmitted, a phenomenon, in which a waveform of a signal which is originally a rectangular wave changes to a wave with delayed rising edge time, that is, a so-called dulled waveform, occurs on a reception side.
In addition, such a digital signal is a combination of a High signal “1” and a Low signal “0”. Thus, the digital signal has, for example, a portion where signals of “1” or “0” continue as in “11110000” and a portion where reversal is repeated as in “1010”. In this case, a sufficient reception level can be reserved in a portion where signals of the same level continue. However, in a portion where signals repeat reversal, it is likely that a signal is reversed due to a transient phenomenon before the signal reaches a predetermined signal level and a sufficient reception level cannot be reserved.
In addition, in the case in which a digital signal of several GHz is transmitted, in a reversed signal after signals of the same level continue, a signal level is smaller due to a conductor skin effect and a transient phenomenon as a frequency is higher or a transmission distance is longer. Jitters in this case are also increased, which causes a so-called code error.